package chi
// Radix tree implementation below is a based on the original work by
// Armon Dadgar in https://github.com/armon/go-radix/blob/master/radix.go
// (MIT licensed). It's been heavily modified for use as a HTTP routing tree.
import (
"fmt"
"math"
"net/http"
"regexp"
"sort"
"strconv"
"strings"
)
type methodTyp int
const (
mSTUB methodTyp = 1 << iota
mCONNECT
mDELETE
mGET
mHEAD
mOPTIONS
mPATCH
mPOST
mPUT
mTRACE
)
var mALL = mCONNECT | mDELETE | mGET | mHEAD |
mOPTIONS | mPATCH | mPOST | mPUT | mTRACE
var methodMap = map[string]methodTyp{
http.MethodConnect: mCONNECT,
http.MethodDelete: mDELETE,
http.MethodGet: mGET,
http.MethodHead: mHEAD,
http.MethodOptions: mOPTIONS,
http.MethodPatch: mPATCH,
http.MethodPost: mPOST,
http.MethodPut: mPUT,
http.MethodTrace: mTRACE,
}
// RegisterMethod adds support for custom HTTP method handlers, available
// via Router#Method and Router#MethodFunc
func RegisterMethod(method string) {
if method == "" {
return
}
method = strings.ToUpper(method)
if _, ok := methodMap[method]; ok {
return
}
n := len(methodMap)
if n > strconv.IntSize {
panic(fmt.Sprintf("chi: max number of methods reached (%d)", strconv.IntSize))
}
mt := methodTyp(math.Exp2(float64(n)))
methodMap[method] = mt
mALL |= mt
}
type nodeTyp uint8
const (
ntStatic nodeTyp = iota // /home
ntRegexp // /{id:[0-9]+}
ntParam // /{user}
ntCatchAll // /api/v1/*
)
type node struct {
// node type: static, regexp, param, catchAll
typ nodeTyp
// first byte of the prefix
label byte
// first byte of the child prefix
tail byte
// prefix is the common prefix we ignore
prefix string
// regexp matcher for regexp nodes
rex *regexp.Regexp
// HTTP handler endpoints on the leaf node
endpoints endpoints
// subroutes on the leaf node
subroutes Routes
// child nodes should be stored in-order for iteration,
// in groups of the node type.
children [ntCatchAll + 1]nodes
}
// endpoints is a mapping of http method constants to handlers
// for a given route.
type endpoints map[methodTyp]*endpoint
type endpoint struct {
// endpoint handler
handler http.Handler
// pattern is the routing pattern for handler nodes
pattern string
// parameter keys recorded on handler nodes
paramKeys []string
}
func (s endpoints) Value(method methodTyp) *endpoint {
mh, ok := s[method]
if !ok {
mh = &endpoint{}
s[method] = mh
}
return mh
}
func (n *node) InsertRoute(method methodTyp, pattern string, handler http.Handler) *node {
var parent *node
search := pattern
for {
// Handle key exhaustion
if len(search) == 0 {
// Insert or update the node's leaf handler
n.setEndpoint(method, handler, pattern)
return n
}
// We're going to be searching for a wild node next,
// in this case, we need to get the tail
var label = search[0]
var segTail byte
var segEndIdx int
var segTyp nodeTyp
var segRexpat string
if label == '{' || label == '*' {
segTyp, _, segRexpat, segTail, _, segEndIdx = patNextSegment(search)
}
var prefix string
if segTyp == ntRegexp {
prefix = segRexpat
}
// Look for the edge to attach to
parent = n
n = n.getEdge(segTyp, label, segTail, prefix)
// No edge, create one
if n == nil {
child := &node{label: label, tail: segTail, prefix: search}
hn := parent.addChild(child, search)
hn.setEndpoint(method, handler, pattern)
return hn
}
// Found an edge to match the pattern
if n.typ > ntStatic {
// We found a param node, trim the param from the search path and continue.
// This param/wild pattern segment would already be on the tree from a previous
// call to addChild when creating a new node.
search = search[segEndIdx:]
continue
}
// Static nodes fall below here.
// Determine longest prefix of the search key on match.
commonPrefix := longestPrefix(search, n.prefix)
if commonPrefix == len(n.prefix) {
// the common prefix is as long as the current node's prefix we're attempting to insert.
// keep the search going.
search = search[commonPrefix:]
continue
}
// Split the node
child := &node{
typ: ntStatic,
prefix: search[:commonPrefix],
}
parent.replaceChild(search[0], segTail, child)
// Restore the existing node
n.label = n.prefix[commonPrefix]
n.prefix = n.prefix[commonPrefix:]
child.addChild(n, n.prefix)
// If the new key is a subset, set the method/handler on this node and finish.
search = search[commonPrefix:]
if len(search) == 0 {
child.setEndpoint(method, handler, pattern)
return child
}
// Create a new edge for the node
subchild := &node{
typ: ntStatic,
label: search[0],
prefix: search,
}
hn := child.addChild(subchild, search)
hn.setEndpoint(method, handler, pattern)
return hn
}
}
// addChild appends the new `child` node to the tree using the `pattern` as the trie key.
// For a URL router like chi's, we split the static, param, regexp and wildcard segments
// into different nodes. In addition, addChild will recursively call itself until every
// pattern segment is added to the url pattern tree as individual nodes, depending on type.
func (n *node) addChild(child *node, prefix string) *node {
search := prefix
// handler leaf node added to the tree is the child.
// this may be overridden later down the flow
hn := child
// Parse next segment
segTyp, _, segRexpat, segTail, segStartIdx, segEndIdx := patNextSegment(search)
// Add child depending on next up segment
switch segTyp {
case ntStatic:
// Search prefix is all static (that is, has no params in path)
// noop
default:
// Search prefix contains a param, regexp or wildcard
if segTyp == ntRegexp {
rex, err := regexp.Compile(segRexpat)
if err != nil {
panic(fmt.Sprintf("chi: invalid regexp pattern '%s' in route param", segRexpat))
}
child.prefix = segRexpat
child.rex = rex
}
if segStartIdx == 0 {
// Route starts with a param
child.typ = segTyp
if segTyp == ntCatchAll {
segStartIdx = -1
} else {
segStartIdx = segEndIdx
}
if segStartIdx < 0 {
segStartIdx = len(search)
}
child.tail = segTail // for params, we set the tail
if segStartIdx != len(search) {
// add static edge for the remaining part, split the end.
// its not possible to have adjacent param nodes, so its certainly
// going to be a static node next.
search = search[segStartIdx:] // advance search position
nn := &node{
typ: ntStatic,
label: search[0],
prefix: search,
}
hn = child.addChild(nn, search)
}
} else if segStartIdx > 0 {
// Route has some param
// starts with a static segment
child.typ = ntStatic
child.prefix = search[:segStartIdx]
child.rex = nil
// add the param edge node
search = search[segStartIdx:]
nn := &node{
typ: segTyp,
label: search[0],
tail: segTail,
}
hn = child.addChild(nn, search)
}
}
n.children[child.typ] = append(n.children[child.typ], child)
n.children[child.typ].Sort()
return hn
}
func (n *node) replaceChild(label, tail byte, child *node) {
for i := 0; i < len(n.children[child.typ]); i++ {
if n.children[child.typ][i].label == label && n.children[child.typ][i].tail == tail {
n.children[child.typ][i] = child
n.children[child.typ][i].label = label
n.children[child.typ][i].tail = tail
return
}
}
panic("chi: replacing missing child")
}
func (n *node) getEdge(ntyp nodeTyp, label, tail byte, prefix string) *node {
nds := n.children[ntyp]
for i := 0; i < len(nds); i++ {
if nds[i].label == label && nds[i].tail == tail {
if ntyp == ntRegexp && nds[i].prefix != prefix {
continue
}
return nds[i]
}
}
return nil
}
func (n *node) setEndpoint(method methodTyp, handler http.Handler, pattern string) {
// Set the handler for the method type on the node
if n.endpoints == nil {
n.endpoints = make(endpoints, 0)
}
paramKeys := patParamKeys(pattern)
if method&mSTUB == mSTUB {
n.endpoints.Value(mSTUB).handler = handler
}
if method&mALL == mALL {
h := n.endpoints.Value(mALL)
h.handler = handler
h.pattern = pattern
h.paramKeys = paramKeys
for _, m := range methodMap {
h := n.endpoints.Value(m)
h.handler = handler
h.pattern = pattern
h.paramKeys = paramKeys
}
} else {
h := n.endpoints.Value(method)
h.handler = handler
h.pattern = pattern
h.paramKeys = paramKeys
}
}
func (n *node) FindRoute(rctx *Context, method methodTyp, path string) (*node, endpoints, http.Handler) {
// Reset the context routing pattern and params
rctx.routePattern = ""
rctx.routeParams.Keys = rctx.routeParams.Keys[:0]
rctx.routeParams.Values = rctx.routeParams.Values[:0]
// Find the routing handlers for the path
rn := n.findRoute(rctx, method, path)
if rn == nil {
return nil, nil, nil
}
// Record the routing params in the request lifecycle
rctx.URLParams.Keys = append(rctx.URLParams.Keys, rctx.routeParams.Keys...)
rctx.URLParams.Values = append(rctx.URLParams.Values, rctx.routeParams.Values...)
// Record the routing pattern in the request lifecycle
if rn.endpoints[method].pattern != "" {
rctx.routePattern = rn.endpoints[method].pattern
rctx.RoutePatterns = append(rctx.RoutePatterns, rctx.routePattern)
}
return rn, rn.endpoints, rn.endpoints[method].handler
}
// Recursive edge traversal by checking all nodeTyp groups along the way.
// It's like searching through a multi-dimensional radix trie.
func (n *node) findRoute(rctx *Context, method methodTyp, path string) *node {
nn := n
search := path
for t, nds := range nn.children {
ntyp := nodeTyp(t)
if len(nds) == 0 {
continue
}
var xn *node
xsearch := search
var label byte
if search != "" {
label = search[0]
}
switch ntyp {
case ntStatic:
xn = nds.findEdge(label)
if xn == nil || !strings.HasPrefix(xsearch, xn.prefix) {
continue
}
xsearch = xsearch[len(xn.prefix):]
case ntParam, ntRegexp:
// short-circuit and return no matching route for empty param values
if xsearch == "" {
continue
}
// serially loop through each node grouped by the tail delimiter
for idx := 0; idx < len(nds); idx++ {
xn = nds[idx]
// label for param nodes is the delimiter byte
p := strings.IndexByte(xsearch, xn.tail)
if p < 0 {
if xn.tail == '/' {
p = len(xsearch)
} else {
continue
}
}
if ntyp == ntRegexp && xn.rex != nil {
if xn.rex.Match([]byte(xsearch[:p])) == false {
continue
}
} else if strings.IndexByte(xsearch[:p], '/') != -1 {
// avoid a match across path segments
continue
}
rctx.routeParams.Values = append(rctx.routeParams.Values, xsearch[:p])
xsearch = xsearch[p:]
break
}
default:
// catch-all nodes
rctx.routeParams.Values = append(rctx.routeParams.Values, search)
xn = nds[0]
xsearch = ""
}
if xn == nil {
continue
}
// did we find it yet?
if len(xsearch) == 0 {
if xn.isLeaf() {
h, _ := xn.endpoints[method]
if h != nil && h.handler != nil {
rctx.routeParams.Keys = append(rctx.routeParams.Keys, h.paramKeys...)
return xn
}
// flag that the routing context found a route, but not a corresponding
// supported method
rctx.methodNotAllowed = true
}
}
// recursively find the next node..
fin := xn.findRoute(rctx, method, xsearch)
if fin != nil {
return fin
}
// Did not find final handler, let's remove the param here if it was set
if xn.typ > ntStatic {
if len(rctx.routeParams.Values) > 0 {
rctx.routeParams.Values = rctx.routeParams.Values[:len(rctx.routeParams.Values)-1]
}
}
}
return nil
}
func (n *node) findEdge(ntyp nodeTyp, label byte) *node {
nds := n.children[ntyp]
num := len(nds)
idx := 0
switch ntyp {
case ntStatic, ntParam, ntRegexp:
i, j := 0, num-1
for i <= j {
idx = i + (j-i)/2
if label > nds[idx].label {
i = idx + 1
} else if label < nds[idx].label {
j = idx - 1
} else {
i = num // breaks cond
}
}
if nds[idx].label != label {
return nil
}
return nds[idx]
default: // catch all
return nds[idx]
}
}
func (n *node) isEmpty() bool {
for _, nds := range n.children {
if len(nds) > 0 {
return false
}
}
return true
}
func (n *node) isLeaf() bool {
return n.endpoints != nil
}
func (n *node) findPattern(pattern string) bool {
nn := n
for _, nds := range nn.children {
if len(nds) == 0 {
continue
}
n = nn.findEdge(nds[0].typ, pattern[0])
if n == nil {
continue
}
var idx int
var xpattern string
switch n.typ {
case ntStatic:
idx = longestPrefix(pattern, n.prefix)
if idx < len(n.prefix) {
continue
}
case ntParam, ntRegexp:
idx = strings.IndexByte(pattern, '}') + 1
case ntCatchAll:
idx = longestPrefix(pattern, "*")
default:
panic("chi: unknown node type")
}
xpattern = pattern[idx:]
if len(xpattern) == 0 {
return true
}
return n.findPattern(xpattern)
}
return false
}
func (n *node) routes() []Route {
rts := []Route{}
n.walk(func(eps endpoints, subroutes Routes) bool {
if eps[mSTUB] != nil && eps[mSTUB].handler != nil && subroutes == nil {
return false
}
// Group methodHandlers by unique patterns
pats := make(map[string]endpoints, 0)
for mt, h := range eps {
if h.pattern == "" {
continue
}
p, ok := pats[h.pattern]
if !ok {
p = endpoints{}
pats[h.pattern] = p
}
p[mt] = h
}
for p, mh := range pats {
hs := make(map[string]http.Handler, 0)
if mh[mALL] != nil && mh[mALL].handler != nil {
hs["*"] = mh[mALL].handler
}
for mt, h := range mh {
if h.handler == nil {
continue
}
m := methodTypString(mt)
if m == "" {
continue
}
hs[m] = h.handler
}
rt := Route{p, hs, subroutes}
rts = append(rts, rt)
}
return false
})
return rts
}
func (n *node) walk(fn func(eps endpoints, subroutes Routes) bool) bool {
// Visit the leaf values if any
if (n.endpoints != nil || n.subroutes != nil) && fn(n.endpoints, n.subroutes) {
return true
}
// Recurse on the children
for _, ns := range n.children {
for _, cn := range ns {
if cn.walk(fn) {
return true
}
}
}
return false
}
// patNextSegment returns the next segment details from a pattern:
// node type, param key, regexp string, param tail byte, param starting index, param ending index
func patNextSegment(pattern string) (nodeTyp, string, string, byte, int, int) {
ps := strings.Index(pattern, "{")
ws := strings.Index(pattern, "*")
if ps < 0 && ws < 0 {
return ntStatic, "", "", 0, 0, len(pattern) // we return the entire thing
}
// Sanity check
if ps >= 0 && ws >= 0 && ws < ps {
panic("chi: wildcard '*' must be the last pattern in a route, otherwise use a '{param}'")
}
var tail byte = '/' // Default endpoint tail to / byte
if ps >= 0 {
// Param/Regexp pattern is next
nt := ntParam
// Read to closing } taking into account opens and closes in curl count (cc)
cc := 0
pe := ps
for i, c := range pattern[ps:] {
if c == '{' {
cc++
} else if c == '}' {
cc--
if cc == 0 {
pe = ps + i
break
}
}
}
if pe == ps {
panic("chi: route param closing delimiter '}' is missing")
}
key := pattern[ps+1 : pe]
pe++ // set end to next position
if pe < len(pattern) {
tail = pattern[pe]
}
var rexpat string
if idx := strings.Index(key, ":"); idx >= 0 {
nt = ntRegexp
rexpat = key[idx+1:]
key = key[:idx]
}
if len(rexpat) > 0 {
if rexpat[0] != '^' {
rexpat = "^" + rexpat
}
if rexpat[len(rexpat)-1] != '$' {
rexpat = rexpat + "$"
}
}
return nt, key, rexpat, tail, ps, pe
}
// Wildcard pattern as finale
if ws < len(pattern)-1 {
panic("chi: wildcard '*' must be the last value in a route. trim trailing text or use a '{param}' instead")
}
return ntCatchAll, "*", "", 0, ws, len(pattern)
}
func patParamKeys(pattern string) []string {
pat := pattern
paramKeys := []string{}
for {
ptyp, paramKey, _, _, _, e := patNextSegment(pat)
if ptyp == ntStatic {
return paramKeys
}
for i := 0; i < len(paramKeys); i++ {
if paramKeys[i] == paramKey {
panic(fmt.Sprintf("chi: routing pattern '%s' contains duplicate param key, '%s'", pattern, paramKey))
}
}
paramKeys = append(paramKeys, paramKey)
pat = pat[e:]
}
}
// longestPrefix finds the length of the shared prefix
// of two strings
func longestPrefix(k1, k2 string) int {
max := len(k1)
if l := len(k2); l < max {
max = l
}
var i int
for i = 0; i < max; i++ {
if k1[i] != k2[i] {
break
}
}
return i
}
func methodTypString(method methodTyp) string {
for s, t := range methodMap {
if method == t {
return s
}
}
return ""
}
type nodes []*node
// Sort the list of nodes by label
func (ns nodes) Sort() { sort.Sort(ns); ns.tailSort() }
func (ns nodes) Len() int { return len(ns) }
func (ns nodes) Swap(i, j int) { ns[i], ns[j] = ns[j], ns[i] }
func (ns nodes) Less(i, j int) bool { return ns[i].label < ns[j].label }
// tailSort pushes nodes with '/' as the tail to the end of the list for param nodes.
// The list order determines the traversal order.
func (ns nodes) tailSort() {
for i := len(ns) - 1; i >= 0; i-- {
if ns[i].typ > ntStatic && ns[i].tail == '/' {
ns.Swap(i, len(ns)-1)
return
}
}
}
func (ns nodes) findEdge(label byte) *node {
num := len(ns)
idx := 0
i, j := 0, num-1
for i <= j {
idx = i + (j-i)/2
if label > ns[idx].label {
i = idx + 1
} else if label < ns[idx].label {
j = idx - 1
} else {
i = num // breaks cond
}
}
if ns[idx].label != label {
return nil
}
return ns[idx]
}
// Route describes the details of a routing handler.
type Route struct {
Pattern string
Handlers map[string]http.Handler
SubRoutes Routes
}
// WalkFunc is the type of the function called for each method and route visited by Walk.
type WalkFunc func(method string, route string, handler http.Handler, middlewares ...func(http.Handler) http.Handler) error
// Walk walks any router tree that implements Routes interface.
func Walk(r Routes, walkFn WalkFunc) error {
return walk(r, walkFn, "")
}
func walk(r Routes, walkFn WalkFunc, parentRoute string, parentMw ...func(http.Handler) http.Handler) error {
for _, route := range r.Routes() {
mws := make([]func(http.Handler) http.Handler, len(parentMw))
copy(mws, parentMw)
mws = append(mws, r.Middlewares()...)
if route.SubRoutes != nil {
if err := walk(route.SubRoutes, walkFn, parentRoute+route.Pattern, mws...); err != nil {
return err
}
continue
}
for method, handler := range route.Handlers {
if method == "*" {
// Ignore a "catchAll" method, since we pass down all the specific methods for each route.
continue
}
fullRoute := parentRoute + route.Pattern
if chain, ok := handler.(*ChainHandler); ok {
if err := walkFn(method, fullRoute, chain.Endpoint, append(mws, chain.Middlewares...)...); err != nil {
return err
}
} else {
if err := walkFn(method, fullRoute, handler, mws...); err != nil {
return err
}
}
}
}
return nil
}